notes on lecture 39 from ecology lectures in Biology 1a at the university of Glasgow

lecture 39 — ecology of
populations

population:
= a group of individuals of the same species that are interbreeding freely

same species

same habitat

use same resources

individuals interact



1. populations are members of the same species

2. populations are defined by physical boundaries

3. populations use the same resources

food

water

breeding sites

roosting sites

over-wintering habitat

4. individuals in populations interact

breeding

competition for resources
intraspecific competition = competition for resources between members of the same
population/species




lecture 39 — ecology of populations 1

, interspecific competition = competition for resources between members of different
populations/species



three important population concepts:

1. populations have structure

2. populations expand and contract

3. populations are regulated




1. population structure
age structure and mortality
number of indivdiuals declines as age increases
three types of survivorship curves

type 2: straight line, diagonal from young to old. constant gradient— mortality
rate is the same (same probability of dying) throughout

type 1: curved— gradient becomes steeper with age. survivorship for young is
very high, mortality rate for old is very high

type 3: curved— gradient becomes more shallow with age. mortality rate is very
high for young, then decreases over time

variation in mortality pattern— can be predicted from life-history strategy and
environment
type 1:

mortality is highest in older age classes

found in long lives species

living in a stable environment

iteroparous (reproduction spread throughout lifetime)

type 3:

high mortality in juveniles



lecture 39 — ecology of populations 2